Project 4 will focus on defining autoimmune autonomic neuropathy (AAN) as an antibody-mediated disorder and will evaluate features of antibody-mediated autonomic failure that may be relevant to other dysautonomic syndromes. Studies in this project will provide a direct translational component to the clinical studies of AAN in Project 1 (Dr. Phillip Low) and physiological and serological correlates to the clinical studies of orthostatic tachycardia syndrome (POTS) in Projects 1 and 3 (Dr. Michael Joyner).